# How to update a Minecraft mod to 26.3 (2026 guide)

> How to update a Minecraft mod to 26.3: new Loom and Gradle versions, Java 25, Mojang mappings and the Fabric API changes that break old code.

Source: https://synagy.org/blog/update-minecraft-mod-to-26-3
Published: 2026-11-05
By: the Synagy team (https://synagy.org)

**Short answer:** to update a Minecraft mod to 26.3, bump Minecraft, Fabric Loader 0.19.5, Loom 1.17 and Fabric API in `gradle.properties`, move Gradle to 9.6.0, then fix what no longer compiles. A mod from 26.2 mostly needs small API fixes. A mod from 1.21.11 or older needs more: Java 25, Mojang mappings and a new Loom plugin first. Versions below were checked on 2026-11-05.

This guide is for people who made a Fabric mod and want it to run on the new version. If you only want to play mods on 26.3, read our guide on [how to install Fabric mods on Minecraft 26.3](https://synagy.org/blog/install-fabric-mods-minecraft-26-3) instead.

## What changed in Minecraft 26.3 for mod makers?

Minecraft 26.3, the Wilderness Bound game drop, came out on 15 September 2026. The [Fabric for Minecraft 26.3 post](https://fabricmc.net/2026/09/15/263.html) lists what changed for modders. These are the changes most likely to break your code:

- **Removed Fabric API classes:** `CompostingChanceRegistry`, `FuelRegistry`, `FabricPotionBrewingBuilder` and the strippable, tillable and flattenable block registries are gone.
- **Item components instead:** compost chance, furnace fuel and brewing fuel now come from item components such as `DataComponents.COOKING_FUEL`.
- **Data-driven brewing:** brewing recipes are now JSON files in the `recipe` folder.
- **New block transformers:** stripping and tilling move to a `block_transformer` data type.
- **SDL instead of GLFW:** input no longer uses GLFW. Fabric warns you not to hardcode keys around `InputConstants`.

**26.3 | Minecraft version, released 15 September 2026**

- **1.17**: Loom version Fabric recommends for 26.3
- **9.6.0**: Gradle version Fabric recommends for 26.3
- **25**: minimum Java version since Minecraft 26.1

## How much work is it from your version?

The answer depends on where your mod is today. The big break came with 26.1, not 26.3. The [Fabric for Minecraft 26.1 post](https://fabricmc.net/2026/03/14/261.html) says 26.1 is the first unobfuscated version. Because of that, no mod from 1.21.11 or before works without at least a recompile.

| Your mod is on | What you have to do | Typical work |
|---|---|---|
| 26.2 | New versions, then the 26.3 API changes above | Least |
| 26.1 | Also the 26.2 changes, such as raw OpenGL calls moving to Blaze3D | More |
| 1.21.11 or older | Java 25, Yarn to Mojang mappings, new Loom plugin, then everything above | Most |

The [Fabric for Minecraft 26.2 post](https://fabricmc.net/2026/06/15/262.html) explains the 26.2 rendering change. Mods that call OpenGL directly instead of going through Blaze3D must migrate.

## How do you update a Fabric mod to 26.3, step by step?

Work in a copy or a new git branch, so the old version stays buildable. Then follow these steps.

**Update a Fabric mod to 26.3**

1. **Back up**: new git branch, old build still works
2. **Fix mappings**: only if you come from 1.21.11 or older
3. **Bump versions**: Gradle 9.6.0, Loom 1.17, Loader 0.19.5
4. **Fix the code**: removed classes, components, input
5. **Test**: client, then a dedicated server

1. **Back up your project.** Commit everything, then create a branch such as `port-26.3`.
2. **Migrate mappings if needed.** Yarn is no longer officially supported. The [Fabric guide to migrating mappings](https://docs.fabricmc.net/develop/porting/mappings/) offers Loom's `migrateMappings` task or the Ravel plugin for IntelliJ IDEA. Ravel also handles Kotlin. Check Mixins by hand afterwards.
3. **Switch the Loom plugin.** Coming from 1.21.11 or older, use `net.fabricmc.fabric-loom`. Replace `modImplementation` with `implementation` and `remapJar` with `jar`.
4. **Update Gradle.** Run `./gradlew wrapper --gradle-version latest`, as the [official Fabric porting docs](https://docs.fabricmc.net/develop/porting/) suggest.
5. **Bump the versions.** In `gradle.properties`, set Minecraft to 26.3, Loader to 0.19.5, Loom to 1.17 and the newest Fabric API build for 26.3.
6. **Refresh and build.** Run `./gradlew --refresh-dependencies`, then `./gradlew build`. Every red line is now your to-do list.
7. **Fix the code.** Move fuel and compost values to item components, and brewing to JSON recipes. Replace removed registries with block transformers.
8. **Update `fabric.mod.json`.** Change the `minecraft` entry under `depends`, for example to `~26.3`.
9. **Test twice.** Use `runClient` for the game and `runServer` for a dedicated server. Many crashes only show up on the server.

> **Tip:** you need Java 25 for the Gradle JVM since 26.1. Fabric also says IntelliJ IDEA 2025.3 or newer is needed for Mixins to work correctly.

**Test on a copy of your world**

A new version can change world data. Open old worlds only in a copy until the port is tested.

## Is there an AI Minecraft mod updater?

Partly. Coding agents can read compiler errors and suggest fixes. But they guess API names they have never seen, and 26.3 is newer than most of their training data. Treat every AI change like code from a stranger: build it and test it in the game.

Synagy takes a narrower route. Mods you build with [Synagy for Minecraft](https://synagy.org/minecraft) are made on Fabric 26.2. The free Mod Compiler in the Synagy Studio then builds the same mod for Fabric 26.3, Fabric 1.21.1 and NeoForge 26.2.

Every build passes the same game tests on a real server of that version first. Those tests place and mine blocks, craft recipes and spawn mobs.

**Port by hand if … | you wrote the mod in Java yourself and want full control over the code**

- **Use the Mod Compiler if …**: you made the mod with Synagy and need it on 26.3, 1.21.1 or NeoForge

Here is where Synagy stops. It cannot port mods that someone else wrote, or your own hand-written Java mod. Porting other people's open-source mods is in development, but not live yet. NeoForge for 26.3 is also still in development.

Synagy is in a free beta right now. Every account gets 25 Free Credits a day, and payments are paused. Planned plans are on the [pricing page](https://synagy.org/pricing). New to modding? Start with our guide on [how to make a Minecraft mod without coding](https://synagy.org/blog/make-a-minecraft-mod-without-coding).

## FAQ

### Can I just change the version number in fabric.mod.json?

No. That only tells the loader which versions to accept. Your mod still has to compile against 26.3. If it uses removed classes such as `FuelRegistry`, it will crash or fail to load. Rebuild the mod with the new versions and test it.

### Do Minecraft 26.2 mods work on 26.3?

Some do, many do not. Fabric removed several API classes in 26.3 and moved fuel and compost values to item components. A mod that uses none of these may still load. Check the mod page for a 26.3 file before you rely on it.

### Why do mods from 1.21.11 not work on 26.x?

Minecraft 26.1 is the first version without obfuscation. Old mods were built against obfuscated names, so they need at least a recompile with Mojang mappings. Most also need code changes for the API updates in 26.1, 26.2 and 26.3.

### Which Java version do I need to update a mod to 26.3?

You need at least Java 25 for the Gradle JVM. Fabric set this minimum with Minecraft 26.1, and it still applies to 26.3. Set it in your IDE's Gradle settings, not only in your system path.

### Can Synagy update any Minecraft mod to 26.3?

No. The Mod Compiler only rebuilds mods that were made with Synagy, for Fabric 26.3, Fabric 1.21.1 and NeoForge 26.2. Porting other people's open-source mods is in development. Until then, mods made outside Synagy need a manual port.